Among the several types of sonar systems used to detect underwater objects such as submarines, there is one type in which passive hydrophones are deployed in large numbers in a given area and some means is required to insonify the adjacent volume of water so that echoes or reflections from such underwater objects are received at the sonobuoys. The transmitting means, of course, needs only to be of the proper frequency pattern and signal strength to insonify the water in the general volume of interest. In the past such sources have been in the form of large stationary magnetostriction-type radiators, hydromechanical drive mechanisms, etc.
There is a need for an array which can accomplish the desired insonification for a limited period of time, which is relatively small and light, inexpensive, rugged enough to be launched into the ocean from an aircraft and which, when its mission is completed, will sink itself such that it does not remain as a long term underwater obstacle which could interfere with fishing equipment, other subsequently deployed sonars or instrumentation, or submarines.